One thing that can make fully grown and seemingly rational adults suddenly metamorphose into squealing toddlers is food.
I have seen intelligent people with well paid, responsible jobs pull ludicrous faces and make 'Eurrgh' noises when presented with a plate of broccolli.
I once bought some Wild Boar sausages from a farmers market and when I told a couple of people about it they instantly wrinkled their noises, made 'Eurrgh' noises and said that it sounded disgusting.
Why are they disgusting? They are only pretentious pork sausages.
I was once eating a potato salad that contained broccolli that I had made myself when a work colleague asked why I wasn't eating 'normal' food.
Now people have been eating vegetables for thousands of years so surely this is normal. What my colleague was eating was a pasty he had bought from a petrol station with so many flavour enhancers and stabilizers in it that the list of ingredients took up half the packet. How is this considered normal food?
Parents across the world each day face a mealtime battle with sulky kids half-heartedly pushing decent food around their plates and whining because it isn't beige-coloured, lathered in saturated fat and endorsed by a talking cartoon animal. For many of these children this attitude towards food continues into adulthood.
In our culture we are bombarded by companies enticng us to buy mass produced food, so industrially processed that the flavour and smell have to be added chemically. This level of advertising saturation makes it seem that junk food is inevitable but this is not the case.
It's only been in the past 50 years or so that the inustrialisation of food has taken place but it has been so aggressive that many of us think that it has always been this way and are distrustful and wary of food that doesn't come with advertising and colourful packaging.
I think this is one of the reasons why many people build up a preconcieved notion of healthy food and dismiss it out of hand without ever even trying it.
What picky eaters need to do when confronted with a food they have not tried before is to not immediately regress to infanthood but to put it in their mouth, chew and then swallow.
That way if they don't like it they are qualified to say so and don't ever need to eat it again.